Think of it as a digital passport control officer. Every time Gmail wants to sync, YouTube wants to check your subscriptions, or the Play Store wants to verify a purchase, they ask the Account Manager: "Is this user still authenticated?"
Are you using this to or just to update a system service ? Google Account Manager 6.0.1 - APKMirror android google account manager 601 link
Never install a version higher than your Android API level. For error 601, users often need version 4.4.4 (for KitKat) or 5.1 (for Lollipop). Check your Android version in Settings > About Phone . Think of it as a digital passport control officer
Error 601 typically appears during this linking process when: YouTube wants to check your subscriptions