Lori,

the present tense and subjunctive form conjugations of regular er verbs are identical for the grammatical singular person forms - je, tu, il - and the 3rd person plural - ils. 

Only with the nous and vous forms  is there a difference between present and subjunctive, and in these 2 cases, the verb conjugations are identical in subjunctive and  imparfait.

Here it is ‘ le bus ‘ that is the subject of arriver, and ‘ arrive ‘ is in the subjunctive form (3rd person singular), indistinguishable in writing or speech from the present tense form.  It is only identifiable as the subjunctive because we know the rule that in a relative clause following attendre que the verb is in the subjunctive form! Vous is the subject of attendre - attendre needs to be in indicative form, as it is.

One of the wins in learning French - when using these present tense forms of er verbs, the subjunctive holds no significant ‘ fears ‘ at all ! 

https://www.lawlessfrench.com/verb-conjugations/arriver/

 https://www.lawlessfrench.com/verb-conjugations/attendre/

Lori,

Vous arrivez le bus arrive