First make sure that Roundsman has been ran at least once as Admin in order for the Registry keys to install.
If this has been done then:
The below assumes you have admin access to the PC during the install and that you can competently use regedit on the PC in question, please do not undertake any such work if you are unsure.
1) Manually grant the PC user (or Domain Users) write permission on HKLM\SOFTWARE\Access UK and its subkeys using regedit (Right-click key > Permissions > Add user/group > Full Control). This should allow the app to run as a normal user.
2) Make sure the local folder Roundsman has been installed into has read/write permissions for Everyone.
If you still see the error or require advice from support before proceeding please log a support case.