Hello,
I just managed to get the Tygem Go client running on OS X 10.15.7 with Crossover 20.02. Here is how, in case anyone is wondering:
1) Download and install the "BlankKitchenSink windows 7" bottle linked at https://www.codeweavers.com/support/wiki/mac/mactutorial/unsupported_deps (current link https://www.codeweavers.com/xfer/Dependency_archive/Blank_KitchenSink_Win7.cxarchive)
2) Install the "Visual C++ 6.0 (4.2 and 6.0) Redistributable" into this bottle, by using the "Install application" guide. This contains runtime libraries (DLLs) for visual basic and C++ programs including mfc42, mfc42u and msvcp60. NOTE: Crossover warns that this is "incompatible with your current bottle", but I ignored this warning and it seems to work fine anyway!
3) Install Tygem from http://www.tygemgo.com/, current direct link: http://download2.tygembaduk.com/down_global/setup/TygemGlobalSetup.exe
Tygem should now work. If you run Tygem and it doesn't start, use the "Run command" feature of Crossover and enable saving a log file. When I first did this, without step 2 above, I got an error output ending with
Blank_KitchenSink_Win7/drive_c/Program Files/TygemGlobal2.0/TygemGlobal.exe
0023:err:plugplay:process_IOService_Device object 0x4503
0023:err:plugplay:process_IOService_Device object 0x4307
0023:err:plugplay:process_IOService_Device Unable to create plug in interface for USB deviceobject 0x430b
0023:err:plugplay:process_IOService_Device Unable to create plug in interface for USB deviceobject 0x430f
0023:err:plugplay:process_IOService_Device Unable to create plug in interface for USB deviceobject 0x4313
0023:err:plugplay:process_IOService_Device Unable to create plug in interface for USB deviceobject 0x4317
0023:err:plugplay:process_IOService_Device object 0x4113
0023:err:plugplay:process_IOService_Device object 0x5503
0009:fixme:exec:SHELL_execute flags ignored: 0x00000100
0026:err:module:import_dll Library MFC42.DLL (which is needed by L"C:\\Program Files\\TygemGlobal2.0\\DanRtp.dll") not found
0026:err:module:import_dll Library DanRtp.dll (which is needed by L"C:\\Program Files\\TygemGlobal2.0\\INIMng.dll") not found
0026:err:module:import_dll Library MFC42.DLL (which is needed by L"C:\\Program Files\\TygemGlobal2.0\\INIMng.dll") not found
0026:err:module:import_dll Library INIMng.dll (which is needed by L"C:\\Program Files\\TygemGlobal2.0\\TygemGlobal.exe") not found
0026:err:module:LdrInitializeThunk Importing dlls for L"C:\\Program Files\\TygemGlobal2.0\\TygemGlobal.exe" failed, status c0000135
Google then led me to install the VIsual C++ package to get MFC42.DLL. And it worked!