If this is your first time using the credentials tester, the output might be a little unclear. Does it show status for the VM in the left-hand column as 'warning' or 'error'? 'Warning' is more or less normal, because if you look closely there are two tests - connecting to guest OS via RPC, and connecting to guest OS via VIX. You only need one connection method for AAIP to work, but you get a warning from the tester if they don't both work.
"Do not have access rights" sounds like VIX isn't working.
RPC requires network connectivity from the backup server to the guest OS, as well as local administrator rights.
VIX does not require network connectivity, but requires either that UAC is completely disabled or that you specifically use the named "Administrator" account with SID ending in -500; in some cases you have to use that account regardless of UAC.
Note that you can use domain accounts, they just have to have appropriate local permissions.