Thanks for confirming what steps you have tried so far.
The launcher logs for Ubisoft Connect can be found here -
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\logs
For the crashes you are experiencing, I would recommend the following steps on top of what you have already tried -
- Run the game as administrator via the game's .exe file using the files properties option
- Update GPU drivers and Windows OS to latest version (Windows 10 update currently Update 2009 build 20H2)
- Install game to another Hard Drive or SSD drive preferably, if available. Also try installing the game on the same hard drive as your Windows OS.
- Verify the game files to fix any corrupt or missing files
- Disable all background software in Task Manager and try a clean boot/restart of PC
- Make sure the game is whitelisted as not a threat in your anti-virus software
- Do a System File Check (SFC) for any corrupted system files and a CHKDSK for any corrupted hard drives
This support article should explain how to perform some of these solutions -
https://support.ubisoft.com/en-GB/Article/000061047
Can I also ask what kind of crash is it you have experienced? A hard freeze, crash to desktop, black-screen, system reboot?