Hi @evachenchen, welcome to the Streamlit community! 
The pywin32 module provides access to many of the Windows APIs from Python. Apps deployed to Streamlit Sharing are executed in a Linux environment . As such, pywin32 fails to install on non-Windows systems, including Streamlit Community Cloud.
To fix the error, you had to remove pywin32 from your requirements.txt file… which you’ve done since posting here 