It was their job to carry the tabernacle when they traveled. Alternate translation: "When you travel, the Levites must carry the tabernacle" (See: [[rc://en/ta/man/translate/figs-explicit]])
This means that they were to set up their tents around the tabernacle. Alternate translation: "set up their tents around it" (See: [[rc://en/ta/man/translate/figs-idiom]])