Does the Colornote app show up in
W10 Programs and Features? You can access this by right-clicking on the W10 Start Flag on the lower left of your W10 desktop/taskbar. If your app does
NOT show up in Programs and Features, then it's not getting into the W10 registry correctly, and the registry is blocking the installation, or the app is just poorly coded as you mention. Since you have multiple computers to try, the first thing I would do, is to use a computer where you have not yet installed this app.
MAKE CERTAIN THAT YOU HAVE DISABLED YOUR PRIMARY AV (ANTIVIRUS) PROGRAM, INCLUDING WEB SHIELD, E-MAIL SHIELD, AND ANY FIREWALL THAT'S ENABLED!!
No one has yet mentioned this most basic procedure. Installing new apps on Windows PCs without turning off your AV has been a thing since 2003;
that's 14 years now. Without doing that, your AV
(such as built-in Windows Defender, Norton, Avast, McAfee, Trend Micro, etc.) will automatically block
ANY new app from installing into Windows of any version (from W2k-W10) because the heuristics detect and block massive changes to the Registry. Very simple, and very well documented all over the Internet.
If you do this on a computer or computers that have never have your app installed on them, and they still don't install, then yes, I would be leaning to poor coding of the app.
You mentioned you've been using the app on Windows phone for years; but W10 has merged the mobile windows versions and the PC versions, so it's very likely that the company who wrote your Colornote app simply hasn't caught up with the new merge and corrected or compensated for the latest PC version of W10. If you follow my procedure on at least 2 computers that haven't had the app yet installed and it still fails, that's the most likely scenario. Have you tried contacting this company? Are they aware of this problem? Are you the only user of this app on the planet??
Best of luck,
<<<<BIGBEARJEDI>>>>