[NEED HELP] How to run?

I still don't understand – is it possible to run in Xonotic? If so, how? For example, in Quake, you had to use the console to run. What's it like in Xonotic?

Running speed is on by default, you can use +speed and -speed in console, like in Quake, to move at a slower or faster speed (but +speed is on by default)

If you want to learn how to move faster, and see people speeding around servers all over then I have two guides on movement tech (one aimed mostly at the pewpew side, the other firmly aimed at race mode speedrunning) www.youtube.com/watch?v=PF6B7TzvwdM and https://www.youtube.com/watch?v=0rW1a7BrPp0

Running speed is on by default, you can use +speed and -speed in console, like in Quake, to move at a slower or faster speed (but +speed is on by default)

If you want to learn how to move faster, and see people speeding around servers all over then I have two guides on movement tech (one aimed mostly at the pewpew side, the other firmly aimed at race mode speedrunning) www.youtube.com/watch?v=PF6B7TzvwdM and https://www.youtube.com/watch?v=0rW1a7BrPp0

How do I disable the sprint ability for a character by default, and then assign a key to sprint?

Running in Xonotic (+speed, -speed) doesn't work at all, all you can do slow down is +crouch. If you want to make it +crouch by default, you can make a userbind (settings->control, and there you can find a userbind and create -crouch->+crouch bind).
Or in a console an example:
seta userbind29_press -crouch
seta userbind29_release +crouch

bind ctrl "+userbind 29"

This might be not always +crouch but does what you want.
But this all is nonsensical since just walking is already slow, to speed up you simply press "space" and you go fast, that's how the sprint works in Xonotic, which is in fact assigned by a key because you need to jump.

I hope I explained everything and correctly