וְנָסַ֧ע אֹֽהֶל־מוֹעֵ֛ד מַחֲנֵ֥ה הַלְוִיִּ֖ם בְּת֣וֹךְ הַֽמַּחֲנֹ֑ת כַּאֲשֶׁ֤ר יַחֲנוּ֙ כֵּ֣ן יִסָּ֔עוּ אִ֥ישׁ עַל־יָד֖וֹ לְדִגְלֵיהֶֽם׃ (ס)
Then the tent of meeting, with the camp of the Levites, shall set forward in the midst of the camps; as they encamp, so shall they set forward, every man in his place, by their standards.
Rashi on Numbers
ונסע אהל מועד AND THE TENT OF MEETING SHALL SET FORWARD after these two divisions (those of Judah and Reuben), as is shown by the position of this statement in the narrative.
Sforno on Numbers
ונסע...אהל מועד...בתוך המחנה. Between the two flags which have already been mentioned.
Rashbam on Numbers
בתוך המחנות, two flags (six tribes) would journey at the head followed by the parts of the Tabernacle and the Levites. These were followed by the last two flags (six tribes, there being a total of 4 flags.)