Hii! Not a big Mecabricks expert, but...
I need to know some more before I can help you. Are you trying to open one of your models in workshop or in your library, or are you trying to view someone else's model on public Library?
Have you waited a long time for the "loading screen" to go away or finish loading?
On what device are you doing Mecabricks? If you are doing it on a phone or smaller device, or even if your computer is not big enough, sometimes models either take very long to load, or never load. The bigger the model, the harder. I do Mecabricks on my phone sometimes, and even small models can have a hard time loading, constantly showing a white screen that tells me something about how it couldn't load, or error, and then gives me the option to reload.
If you are viewing someone else's model on public Library, wait for the "loading screen" to finish loading, and it should then go to a "building scene screen". Wait a while longer, and it should load the model. If it doesn't, you can try a few more times, and make sure you are connected/have network/wifi. Try disconnecting and then reconnecting.
If you are using a phone or smaller device, follow the same steps as above, but don't be surprised if your device cannot load the model. Try a few times, and then you might need to give up or try again on a different device, especially if the model is bigger.
I hope this was of some help! ♡

it works now

That's good!