1) You need to install ProtocolLib onto your server for the Matrix plugin to work.
2) Looking at your logs, it seems there were issues loading in chunks, which could suggest a lot of entities existing in a "Lazy chunk". For this, I suggest you do the following:
1) Clearing Entities From Console
Without joining the server, follow the steps below on the minehut dashboard's console, not in the server itself. Here is how to do that with the console:
How to clear entities:
1) Press "ACTIVATE" on the server
2) Press "EDIT SERVER" or "CONTINUE" to go to your main server editor
3) Scroll down a little bit and enter the following in the console and press enter:
kill @e[type=! player]
4) Afterwards, wait a few seconds then type "save-all" in the console and enter
5) Restart the server, and try to join.
2) Using Skript To Clear Entities
You will need to have the plugin "Skript" installed on your server. After installing, make sure to restart your server, then you can do the following:
1) Press "ACTIVATE" on the server
2) Press "EDIT SERVER" or "CONTINUE" to go to your main server editor
3) Go to the "FILE MANAGER" tab which can be found from the top
4) Find the folder/directoy named "plugins" and open it
5) Find the folder/directory named "Skript" and open it
6) Find the folder/directory named "scripts" and open it
7) Create a new file, name it whatever you want, but make sure it ends with ".sk" (so, for example, like this: clearentities.sk)
8 ) Open that file and paste the following inside:
every 1 second:
kill all entities
9) Hit save on the bottom, then go to the "APPEARANCE" tab found from the top
10) Find the box named "Server Command" and type the following inside (replace "[file]" with whatever you named the skript file):
sk reload [file]
11) Wait a little bit and then restart your server. See if you can join now.
Hope this helps you out!