Impossible to communicate

I have a supplier who is trying to help a client of mine with the installation of software for a bluetooth operated device. The supplier has a different version of Team Viewer. The client has a later version, despite my sending him the link and asking him to download the Team Viewer version used by the suppler. The supplier tells me : "Teamviewer tell me that customer has a more recent version, not compatible with ours".

I think the supplier has Team Viewer 11, or for sure not the same version as the client.

Is there a workaround?