仲間入り	        850,396		
の仲間入り	433,577		
の仲間入りをし	50,169		
の仲間入りをする	12,633		
の仲間入りし	27,292		
の仲間入りする	5,983

Without a complete example sentence, I don't think the note is that helpful. Also, that particular structure only accounts for ~11% of usage.

@@ -18,3 +18,3 @@
-<s_inf>oft. ～の仲間入り（を）する</s_inf>
-<gloss>becoming a member (of ...)</gloss>
-<gloss>joining the ranks (of ...)</gloss>
+<gloss>joining (a group)</gloss>
+<gloss>becoming a member (of)</gloss>
+<gloss>joining the ranks (of)</gloss>

グループの仲間入り	1157	   <--- standard usage example

Really fun yourei result, "rejoining the ranks of the living":
私はふたたび生きている者の仲間入りをした

仲間入り	850396	61.4%
の仲間入り	433577	31.3%　<--- not a structure you would guess
に仲間入り	99293	7.2%
と仲間入り	1344	0.1%
を仲間入り	1465	0.1%


https://eow.alc.co.jp/search?q=仲間入り
～の仲間入りをする
be included in

～が民主国家の仲間入りをすること
entrance of ~ into the community of democratic nations

チームの仲間入りができたと感じる
feel like a team member


仲間入りをする	13619	40.6%
仲間入りする	19910	59.4% 

yourei:
https://context.reverso.net/translation/japanese-english/仲間入り
勇敢な冒険者の仲間入りができます
You would be joining that rarefied group of brave explorers.

Possibly [exp].

sankoku gives under 仲間 as a collocation simply as ~入り. No definition or example. 

Actually encountered this organically in a story about a teen growing up in Tokyo. Context was surely joining some clique or gang. The previous gloss conceals a rather unusual structure;  It's more like "entering into someone's/some-group's friend group or inner-circle", so the context needs to somehow specify *which* "friend group" you are talking about.  仲間 is otherwise floating here. の is not required if it is evident from context, but ngrams show の is included explicitly more than half of the time.

Some quick yourei collocations:
作者を一躍人気作家の仲間入りさせた
王族の仲間入りを果たした
豪商の仲間入りを果たした
純粋培養の仲間入りをしなくてはいけなかった
私自身も亀の仲間入りをした気持になってくる
スターの仲間入りを果たす
高校進学者の仲間入りをする
おれ達の仲間入りをしないんだ?
....
Obviously there are a million of these (1700 yourei results for 仲間入り)

@@ -18 +18,3 @@
-<gloss>joining a group</gloss>
+<s_inf>oft. ～の仲間入り（を）する</s_inf>
+<gloss>becoming a member (of ...)</gloss>
+<gloss>joining the ranks (of ...)</gloss>

Meikyo vt and vi additions to n,vs entries
-*- via bulkupd.py -*-

@@ -16,0 +17 @@
+<pos>&vi;</pos>