How could I install previous lxd version

[tomp]

LXD does not support installing older unsupported versions.
The LXD 5.xx releases are only supported for 1 month, so to keep up to date with security and bug fixes you should ideally run on latest/stable channel or one of the LTS channels such as 5.0/stable.

See

https://documentation.ubuntu.com/lxd/en/latest/installing/#choose-your-release

Managing the LXD snap package

Introduction The LXD snap produced by the LXD team is the preferred way to consume LXD. This allows the LXD team to distribute all of LXD’s dependencies in one package and have LXD run in a consistent environment whilst allowing it to be installed on many different Linux distributions. This greatly simplifies support as other than the kernel version, everything else is going to be identical on all systems. The snapd packaging system uses the concept of “tracks” and “channels” to allow the user …

We do provide the last few monthly releases as static channels for installing specific versions so as to allow more control as to when the systems are upgraded. However it is still expected that systems are manually upgraded frequently when using these monthly releases.

The article above covers the snap store proxy which would allow you to control exactly which revision your cluster systems get, so that would be a supported way of achieving a specific version.