The Eruv permits carrying on Shabbat / Yom Kippur within the defined Eruv boundaries.
You must check every Friday that the Eruv is functional – only specific authoritative confirmation on Friday validates the Eruv for use that week.
It is most important that the sanctity and dignity of the Synagogue be properly maintained. This refers only to the actual room(s) where services take place; it does not refer to the other parts of the shul complex.