Question

I'm afraid Paul (not/to accept) our offer.​

Answer 1

Past simple - I'm afraid Paul won't accept our offer.​

Present perfect - I'm afraid Paul don't accepted our offer.

Present simple - I'm afraid, Paul always don't accept our offer.​

Present continues - I'm afraid, Paul don't accepting our offer.​

Answer 2

will not accept это правильно

Answer 3

"I'm afraid Paul may not accept our offer."