I use windows on all my computers and I need acrobat dc to send forms to have them filled out or signed. There are two membership options.
1. 12.99/mo and says windows only
2. 14.99/mo and says windows and mac
If I subscribe to option #1 will my clients be able to view the documents I send them if they have a Mac?
You don't say but I think the subscriptions you're talking about are Acrobat Standard and Acrobat Pro. Acrobat Pro does much more. Acrobat Standard does less, but it only runs on Windows.
But that's just the software you are renting. The PDF files you make are viewable by anyone with the right software to view it, Mac or Windows. Forms are a problem though because most people now use software NOT suitable for PDF form filling. Personally I advise using server based HTML forms today, and using PDF only for static documents.