Hi @Anonymous,
Since the return value is Float, so you need to process the Float into an integer, we can use the split function to separate it into integer and decimal parts. Then get the integer part to put into the expression:
int(split(string(outputs('Compose')),'.')[0])
addDays('1899-12-30',outputs('Compose_2'),'yyyy-MM-dd')

This is the result of runs:
I hope it can help you.
Best Regards,
Community Support Team _ Lin Tu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.