Error when doing Temp table

[MinHuynh]

Hi Alex, I wanted to say thank you first for your amazing YouTube videos and I definitely think you've made great guidance for us on the journey of Data Analysis :) I really appreciate you!

I had this issue when creating the CTE: "Arithmetic overflow error converting expression to data type int"
...So, instead of converting the sum of vac.new_vaccinations to INT, I converted to BIGINT instead and it worked.

However, I had this issue: "Implicit conversion from data type datetime to numeric is not allowed. Use the CONVERT function to run this query".
OR ERROR "Arithmetic overflow error converting expression to data type int" (when I don't convert it to bigint like above).

Would you please show me how I can figure this out?
Thank you so much Alex :)