The phrase "follow the rules" is a grammatically correct and usable in written English. You can use it when you want to encourage someone to abide by certain laws or regulations, or when you want to emphasize the importance of following regulations. For example, "If you want to use the school's computer lab, you must follow the rules.".
"We follow the rules".
You follow the rules.
I'll follow the rules".
Bachir cannot follow the rules.
Everybody should follow the rules".
"They don't follow the rules.
I didn't follow the rules.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com