Symptoms

After downloading all necessary files (including the CanonicalGroupLimited.UbuntuonWindows_2004.2021.825.0.AppxBundle file) prior to the installation, the following error message is received during the installation:

Following files are not found in folder 'C:\Users\...': CanonicalGroupLimited.UbuntuonWindows_2004.2021.825.0.AppxBundle."

Cause

Timeline accept only "Ubuntu_2004.2020.424.0_x64.appx" with "Ubuntu2004.exe" inside. Therefore, you must perform a series of renames so that the Timeline Setup can proceed to the next steps of the installation wizard.

Resolution

1. Rename the CanonicalGroupLimited.UbuntuonWindows_2004.2021.825.0.AppxBundle (which is currently downloading via the link Ubuntu2004) file with ZIP extension.
2. Unzip CanonicalGroupLimited.UbuntuonWindows_2004.2021.825.0.zip 
3. In the unzipped files find the Ubuntu_2004.2021.825.0_x64.aspx file and rename it to Ubuntu_2004.2020.424.0_x64.
4. Unzip Ubuntu_2004.2020.424.0_x64.zip 
5. In the unzipped files find the ubuntu.exe file and rename it to ubuntu2004.exe  
6. Zip all files including the renamed ubuntu2004.exe with the name Ubuntu_2004.2020.424.0_x64.zip 
7. Rename Ubuntu_2004.2020.424.0_x64.zip file with appx extension. So you should end up with Ubuntu_2004.2020.424.0_x64.appx