Can´t use text as results for CASE WHEN statements

I try to use '<2 months' as a result for the CASE WHEN but I get an error that says:

invalid input syntax for integer: "<2 months"

This leads me to believe that it is expecting an integer as a result, and when I put integers, the code works. But I thought I could use strings to group the conditions however I liked.

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I found the answer, the ELSE 0 line was forcing the other statements to be integers