3 When both are sounded, the whole community is to assemble before you at the entrance to the tent of meeting.

Read Numbers 10:3 Using Other Translations

And when they shall blow with them, all the assembly shall assemble themselves to thee at the door of the tabernacle of the congregation.
And when both are blown, all the congregation shall gather themselves to you at the entrance of the tent of meeting.
When both trumpets are blown, everyone must gather before you at the entrance of the Tabernacle.