First steps

/spawnersadmin give <you> zombie 3 hands you one item holding three zombie spawners of tier 1. The item's name says how many it holds: ZOMBIE SPAWNER [3x].

Place the item like any block. The three spawners become one stack in one block, owned by you. A hologram over it shows the type, the stack, the tier and how full the storage is.

Get another item with /spawnersadmin give <you> zombie 5 and right-click the placed spawner with it: one spawner goes in. Sneak and right-click and the rest of the item goes in, up to the tier's stack limit (64 for tier 1).

Stand within 16 blocks. Every 20 seconds the stack makes two zombies per spawner. No zombie appears: their rotten flesh, iron, carrots and potatoes go into the storage, and their experience with them.

Right-click the spawner with an empty hand. The hub shows the stack, the owner, the mode, the time until the next cycle and how full the storage is, all moving while it is open.

Open Storage. Click an item to take one, right-click for a stack, shift-click for all of it. Claim experience repairs your Mending items first. Sell all sells everything that has a price; with ExyliaMarket installed its worth list sets the prices.

Open Upgrades from the hub. Each of the four tracks (speed, amount, storage, experience) shows its current and next value and the price of the next level.

Mine the spawner with a pickaxe that has Silk Touch: one spawner leaves the stack and goes into your inventory. Sneak while mining to take the whole stack. The last spawner cannot be mined while the storage holds anything, so empty it first.