Astrill VPN causing a crash?

[Farkas]

Just got an answer from the Astrill support. They tried a lot of things but nothing worked so far.

After telling them my phone configuration, they told me the following :

@Astrill support team

It seems that you are running an android Custom ROM or Cooked-ROM that is causing the issue. Since a custom ROM removes some of the bloatwares and other features of an android firmware, there is a chance that the installed LineageOS does not have the complete features, ports and other necessary tools required and is used by the astrill application. Please proceed with flashing the phone with a stock Android firmware and try to install astrill application again.

Anyone has any idea about this ? Since i really need that vpn to access Google and WhatsApp or Facebook in China, do i have to downgrade to LOS 14 to make it work ?