That is a discussion you will have to have with him IF he can still efile 2018 returns ... not all tax pros can do that after the filing season closes. If he is not willing to take the responsibility of letting you use his professional program then that is on him ... personally I would not let anyone use my program for any reason. If you are not a tax professional you will probably get very lost ... it is not written for the DIY user ... it has no interview to follow.
Next ... you can still have direct deposit even it you mail it in. If you want to use the TT 2018 downloaded program to complete a return then hand a signed paper copy in to him to transmit (and he agrees) then go ahead. Of course he will have to input what you did and if he believes the return to be incorrect or unfactual he has the right and duty to refuse filing your return. Again that is a conversation you need to have with him.
