Garrys Mod Not starting

[The-man-who-knows-nothing]

I'm probs being thick as anything RN however I can't seem to get Garrys Mod up and running, I hit start and i get this " Application State: Unable to run" and the log is totally empty, I can run MC fine I just can't figure this out

Redirecting stderr to '/home/amp/Steam/logs/stderr.txt'
[ 0%] Checking for available updates...
[----] Verifying installation...
10:28:45
Steam Console Client (c) Valve Corporation - version 1679680174
-- type 'quit' to exit --
Loading Steam API...OK
force_install_dir 4020
10:28:46
Connecting anonymously to Steam Public...OK
10:28:47
Waiting for client config...OK
Waiting for user info...OK
app_update 4020 validate
Update state (0x5) verifying install, progress: 0.00 (0 / 4066658962)
10:28:49
Update state (0x5) verifying install, progress: 1.43 (58334457 / 4066658962)
10:28:51
Update state (0x5) verifying install, progress: 9.27 (377063195 / 4066658962)
10:28:53
Update state (0x5) verifying install, progress: 18.74 (762014995 / 4066658962)
10:28:55
Update state (0x5) verifying install, progress: 22.80 (927115009 / 4066658962)
10:28:57
Update state (0x5) verifying install, progress: 28.87 (1174054863 / 4066658962)
10:28:59
Update state (0x5) verifying install, progress: 41.69 (1695389345 / 4066658962)
10:29:01
Update state (0x5) verifying install, progress: 54.26 (2206502450 / 4066658962)
10:29:03
Update state (0x5) verifying install, progress: 67.12 (2729578642 / 4066658962)
10:29:05
Update state (0x5) verifying install, progress: 79.01 (3213149124 / 4066658962)
10:29:07
Update state (0x5) verifying install, progress: 90.21 (3668555118 / 4066658962)
10:29:09
Update state (0x5) verifying install, progress: 94.66 (3849660088 / 4066658962)
10:29:18
Success! App '4020' fully installed.
quit
10:29:24
CWorkThreadPool::~CWorkThreadPool: work complete queue not empty, 1 items discarded.
CWorkThreadPool::~CWorkThreadPool: work processing queue not empty: 1 items discarded