Do I have to manually broadcast something? (I watched a video where it says so)
As of now, the transaction is just sitting there with 0 confirmations after 2+ hours.
I think I messed up the fee as I just applied the default fee that was set by Electrum and it was too low so now I'm stuck for hours (maybe even days?)...
The transaction is automatically broadcasted as long as it was signed and you had an internet connection. Infact seeing it on the MEMPOOL shows it was broadcast successfully. It will eventually get confirmed as long as the fee isn't below purge fee. You can check the fees on the MEMPOOL the lower the priority the slower it gets confirmed.
Use your transaction hash to check on the MEMPOOL if RBF is enabled on the transaction so you can adjust the fees if you want it confirmed faster.