I have had trouble with recent invites too.  I have an acct. with QBO, so maybe start with signing up for one (free month). Then use a private window when you accept.  That seem to do the trick (for me).  If not, contact support.

Resolution for 'accepting the invite issue: 'I’m assisting with the bookkeeping of our local Speed Skating club as a volunteer and they’ve invited me as a user but I keep getting and error when accepting the invite.' available: Yes.

The accepting the invite issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the accepting the invite issue yourself by looking for a resolution described in the article. If it is a complex accepting the invite issue or you are unable to solve the issue, you may contact us by clicking here or by using other accepting the invite support options.

For more information about resolving issues related to accepting the invite in Quickbooks/QBO or to get support for the issue 'I’m assisting with the bookkeeping of our local Speed Skating club as a volunteer and they’ve invited me as a user but I keep getting and error when accepting the invite.', click the link below: