Link is not the best client portal out there and there are plenty of complaints.  The advantage of using Link is that it comes free with ProConnect tax products and there is some level of integration with the product you use.  That's why some (including me) have moved away from Link and use their own client portal, over which they have more (if not total) control.

Did you even try send out the requests from Link for Accountants?  It will should work.

[Edit: Updated to make sure I don't run afoul of the cardinal rule for writing an opinion 😁]