Hi,
I am giving a test to ActivityWatch on a Windows10 machine, with the ZIP package (no installation needed). And I faced an issue, nothing but the client was running.
And it seems the root cause is to be found in unexpected chars in dir path.
See the content of log with the error message :
2021-02-04 12:34:57 [INFO ]: Searching for bundled modules in: ['C:\\[dhy]\\activitywatch\\aw_qt', 'C:\\[dhy]\\activitywatch'] (aw_qt.manager:67)
2021-02-04 12:34:57 [INFO ]: Found bundled modules: (aw_qt.manager:72)
2021-02-04 12:34:57 [INFO ]: Found system modules: (aw_qt.manager:99)
2021-02-04 12:34:57 [ERROR]: Module aw-server not found (aw_qt.manager:265)
2021-02-04 12:34:57 [ERROR]: Module aw-watcher-afk not found (aw_qt.manager:265)
2021-02-04 12:34:57 [ERROR]: Module aw-watcher-window not found (aw_qt.manager:265)
2021-02-04 12:34:57 [ERROR]: Manager tried to start nonexistent module aw-server (aw_qt.manager:256)
2021-02-04 12:34:57 [ERROR]: Manager tried to start nonexistent module aw-watcher-window (aw_qt.manager:256)
2021-02-04 12:34:57 [ERROR]: Manager tried to start nonexistent module aw-watcher-afk (aw_qt.manager:256)
2021-02-04 12:34:57 [INFO ]: Creating trayicon... (aw_qt.trayicon:200)
2021-02-04 12:34:57 [INFO ]: Initialized aw-qt and trayicon succesfully (aw_qt.trayicon:235)
By just renaming the faulty folder (actually removing the square brackets in its name), problem has been solved.
I guess this is an easy thing to be fixed 
Long life !