Achievement

Use the 'custom trigger' function where it asks for your achievement's trigger.

Then, create a separate procedure with the 'on player update tick' global trigger. Use an 'if' bracket with 'and' functions to check that each of your four items is in the player's inventory. If all four of these conditions are true, use the 'give achievement' function to give the player your achievement.

It should look something like this. You do need to be careful running things on player update tick, as it's very easy to crash the game if you misplace something.

If you're worried about this, you could also just change the global trigger to 'when entity picks up item.' It wouldn't give the advancement if the items were transferred into the inventory via. a menu, but would still probably work in most cases.

If this is the case, it’s more likely that there’s something the item is doing that crashes the game, not the achievement. Nothing in the above procedure, or the ‘picks up item’ variant should really be able to do that. 
What specific error is this giving? And is the actual achievement procedure listed in the crash log as one of the issue sources?

If you look at the crash log, the actual 'error' should be in light red, and it should be followed by a list of procedures that aren't working. (This is just in the 'console' tab of your workspace, and appears every time the client is run.) If it just says 'memory overload,' for example, then something's looping endlessly without a stop condition. More likely, there's a missing dependency somewhere- something might be using 'nearest entity of type,' but not finding an entity, and then trying to run a procedure on nothing. Just a general idea of what the problem is would be helpful!

@InRayYTS

Can you screenshot your console about the error message you get?

You need to upload the file somewhere else, (mediafire, imigur, wix, etc;), and then copy the image URL and link it here. MCreator doesn't store the files itself.

...Haven't really seen something like this before. It looks like something about the 'Heavenly Lord' procedure is causing problems? Could you maybe upload a screenshot of the procedure itself? If you click any of the links there, it will take you to the specific lines in the code that are causing issues, though it looks like it is specifically the advancement that's the source. (Sorry, this probably isn't very helpful.)