Here, Cambridge doesn't use a comma. I am confused. Example in Cambridge Dictionary: Unfortunately we can't come this evening after all.
On different pages i found some rules telling there needs to be a comma. Examples follow:
We do usually put a comma after adverbs like 'unfortunately'. They are called 'sentence adverbs' because they modify the whole sentence and often give the opinion of the speaker/writer.
A parenthetical phrase adding detail to the main clause. Initially placed parentheticals are normally set off by a comma.
Cause I'm studying for my Level 2 graduation, i want going crazy reading here and there comma rules followed by looking in the Cambridge Dictionary without finding them there.
HELP me out please !