How can I connect to older versions of teamviewer with the Teamviewer mobile application?

I am attempting to help my grandmother with a computer issue and cannot connect because the teamviewer 13.2.36220 does not seem to be compatible with the teamviewer mobile application. I am away on business so my first thought was to use my mobile application (android, current version installed). When I recognized this wouldnt work, I attempted to use my work computer to install an older version (we use 15.2.2756) but unfortunatrly I cannot because only our IT staff have admin rights to install new applications. 

What can I do to get my android on 15.8.115 CL, to connect to my grandmother's computer on 13.2.36220 so I can help her out?