@moem It really works with the 0.8.8 beta installer. I successfully finish installing the Ubuntu touch on the Xiaomi Mi A2 device. Thank you so much.

Dear community,
I already tried with UBports to install Ubuntu touch on my Mi A2. But it is not working yet. UBports doesn't respond anything after choosing vendor.img file and press continue.

Here is my progress.

1. Unlocked the phone
2. Developer Options > Enable USB debugging
3. Make sure Android 9
4. Universal ADB Driver Install
5. UBport installer 0.91 Beta detects automatically Mi A2.
6. Choose Ubuntu touch OS.
7. Choose the release version. ( I already try all of them).
8. Select vendor.img file that I downloaded manually.
9. Press continue.

But, UBport doesn't change anything and does not respond.
Please guide me to other options. If it is not necessary, it is better to not root my phone.

Best regards
Sann