If I understand your question correctly, you're looking to create fillable (fill-and-print / fill-and-submit) PDF documents by using an Author instance of AEM Forms in the browser and not using AEM Forms Designer on the desktop.
While you can 'extend' an existing XDP template with an Adaptive Form to create a document of record, you can't create a from-scratch PDF form using the author editor. You still need to use the desktop Designer tool to accomplish this.
If this isn't the case and you are looking at creating AEM Forms in your author instance and then publishing those forms to the publish instance, then absolutely. You can create web-based Adaptive Forms for fill and submit online.
We have sort of open options on where we want to proceed but the latter part of what you mentioned  is more true. In addition to that we want end users to have an option of downloading their filled form as pdf on click of a button (Not right-click print though )
And we want to disable/remove submit button, which is possible it seems.
Can you tell if the pdf part is possible?
In form page properties I tried under Form Model -- "Document of Record Template Configuration" -- Associate form template as the Document of Record template. It provides a search box but not sure what to look for over there. (Later I figured I need to upload a xdp document, not sure how to create that for a form that I am creating, within AEM)
 "If this isn't the case and you are looking at creating AEM Forms in your author instance and then publishing those forms to the publish instance, then absolutely. You can create web-based Adaptive Forms for fill and submit online."
PS - I had this reply in 'Draft for couple of days, forgot to submit it. Thanks to autosave I am able to recover and send it
Hi @snbaem, the main question you had though is whether or not you can author PDF fillable forms using the Adaptive Forms editor (web-based). It is not.
When you have a document of record associated with your form, if you add the Verify step to your form in a separate panel, you'll be able to immediately provide your users with a "your form so far". You can also do the same with the Forms Portal component for your site. The PDF itself is put together server-side so you could definitely script the disappearance of any submit buttons in your existing PDF.
Thanks for prompt reply. If I can ask one more thing here briefly mentioned in my previous comment, how is it possible to have users view the forms published as forms and while they fill the form, have an option to view the form as pdf?
Eg: Authors design the form in author instances and once done publish the forms. The end user can view the form as a form page. If they want to download the form as a pdf (Or say fill the form and download as pdf)how can that be done?
Inside your Adaptive Form, drag and drop the Verify step into a new panel (typically in a separate tab view). When viewed by the user, a PDF will be generated from the XDP defined in your document of record. I'm not a big fan of this approach directly inside forms but it's a quick and easy way to show and allow a download of a PDF during the filling process.
I had tried a bit on the Document of Record, but on author side,. i.e if I point a given form to an .xdp file in repository then on click of DOR, I can get the generated pdf. The option you have suggested in publish side will be very useful to me.
However, the xdp I got was from a sample available online (will add link as I find). How do I generate and .XDP version of my adaptive form ? Moreover, that .XDP has to be in sync with the changes that are being made on the adaptive form as well (right?)
There is another thread I created that has also touched this issue. It seems DarrenBiz has given an answer over there. If you know of any other way to generate XDP from ongoing (being authored) forms, please share
Thanks for the response
If you'd like to generate your DOR from the Adaptive Form, you still need to use a template XDP. This will allow you to generate a document of record from any of your adaptive forms.
If you'd like a more custom view, you'll need to create the XDP using Designer.