How to generate dummies for all holidays (date format = "%M/%d/%Y" ) for all years?

The first problem I can see is that you can´t add a character string (i.e. "11-11") to the POSIXct vector that you are creating with those functions, you would have to add that date in a proper format, see this example.

holidays <- c(Easter(1979:2018),CACanadaDay(1979:2018))@Data
#> [1] "1979-04-15 GMT" "1980-04-06 GMT" "1981-04-19 GMT" "1982-04-11 GMT"
#> [5] "1983-04-03 GMT" "1984-04-22 GMT"

# Adding a date in POSIXct format
holidays <- c(as.POSIXct("2019-11-11"), holidays)
#> [1] "2019-11-11 UTC" "1979-04-15 UTC" "1980-04-06 UTC" "1981-04-19 UTC"
#> [5] "1982-04-11 UTC" "1983-04-03 UTC"

Also, please ask your questions with a Reproducible Example, the way you are sharing your code is very hard to read and understand. If you've never heard of a reprex before, you might want to start by reading this FAQ: