It sounds like the password you're entering is being rejected.
This password prompt is presented by your operating system, and is intended to keep you from accidentally installing software.
If this is your personal machine and you don't need a password to log into the computer when it first starts up, you can probably leave the password blank and click OK to get past this prompt. If this is your personal machine and your normal password isn't working, check to make sure that CAPS LOCK is off, and type the password carefully.
If this is your work machine and it's asking for an Administrator password, well, you'll need to have a conversation with your friendly IT person.
If you're still stumped, you may need to reset the password on your Mac:
Thanks for replying! And so quickly. I used your suggestions, but sadly they made no difference. I have changed passwords over and over (which may be the problem) to no avail. I can't imagine what is wrong. I am so unhappy, especially since I cannot contact Adobe. Apple has a help phone number (with a charge) which I would call if I thought it would help. Maybe this Adobe community help thing will lead to something. Once again, I really appreciate your trying to help, which in itself has made me feel better. I am really frustrated and upset. Jeanie
You're unable to get past the password prompt, even after resetting the password on your mac?
I do get the password prompt. I type it in after changing it. When I click "ok", the box just stays there and shakes. I have tried my Adobe password, my Apple password, and my administrator password. I truly cannot get any farther, and I have literally spent hours every day for at least a month trying to make this work. I am so upset. You have been so patient and seem to be really trying. (As with most hangups on the computer I am inclined to think that there is one very simple box not checked or blank not completed -----one tiny thing that holds up the whole mess.)
Please read my original response carefully. If you've followed the directions carefully, and netiher leaving the password blank nor using the password that you log into the computer itself with work, you'll need to reset the password on your computer. The links in the original response provide instructions from apple on how to do that. You'll need to use the instructions that correspond to your version of MacOS.
If you're still stuck, you'll probably need to contact Apple for support.