The latest version of TeamViewer (15.67.3) doesn't work on Win7 x64. The previous version (15.66.4) does work correctly on Win7. Unless there is an issue with the portable release, the latest version of TeamViewer dropped support for Windows 7. It would be useful to prepare a legacy version of the app.
I can confirm this issue with TeamViewer 15.67.3. The local install has the same issue. When run directly, it yields the typical: "The procedure entry point SetProcessMitigationPolicy could not be located in the dynamic link library KERNEL32.dll." There's no detection or warning before that in the local installer.
It appears the publisher has dropped support for Windows 7 with this newer version with no announcement. Likely 15.66.x is the last version to support it. It now requires Windows 8.0 or later.
I'll check with the publisher about providing a legacy package for Windows 7 users. In the meantime, here is the download for TeamViewer Portable 15.66.4 for Windows 7.
Sometimes, the impossible can become possible, if you're awesome!