plugins auto update doesn't work

Which update: core, or Plugin/Theme/Translation?

Please refer to the FAQ:

Why don’t automatic updates happen right away?
You may find that you receive an update notification, but automatic updates don’t happen right away. That’s okay! WordPress performs automatic updates according to timing based on certain transient values, and it is possible for the update check to happen some time before the automatic update routine executes. The Plugin doesn’t modify the timing of the automatic update routine; rather, it just tells WordPress which update types are enabled.

Also, core now has two separate types of updates: manual updates and automatic updates. When you see the manual upgrade notice, WordPress has received the manual update offer, but has not yet received the automatic update offer. The two offers are fetched based on two different transients, and do not happen at the same time. Automatic core updates are served on a staggered rollout, which means that it may take up to 36 hours for the automatic update to execute after receiving the manual upgrade notice. For Plugins and Themes, you should normally see the automatic update routine execute within 12 hours of receiving the manual upgrade notice.