There are only a few ways you can craft items in AL.

Crafting Non-Magical Equipment

You can craft non-magical (mundane) equipment using gold and downtime days. Please see Downtime Activities for more information.

Crafting Magical Equipment

Bastions

You can only craft magical equipment by using a Bastion. Even then, only common and uncommon items can be crafted. Please see Bastions in AL for more information.

Artificers

Artificers, as part of their class features, can craft certain magical items. Please see the Artificer class rules and the ALPG 15.3 for more information.

Not Tradable

Any crafted magical items are considered “player-created” and are not tradable.

Why Can’t I Craft Using the Rules In the DMG?

The DMG is not a player-facing resource. The ALPG (see Documents) specifically limits what can be used from the DMG. Page 1 limits use of the DMG to backgrounds.

Crafting Ammunition

When crafting ammunition (arrows, bolts, bullets), mundane or magical (through your Bastion), the number of items you craft is equivalent to the bundle size you would normally purchase.

AL Ruling:

The only AL ruling that we have, differing from the core rulebooks, is guidance on smokepowder and it's corresponding number of bullets.

For your question, follow the Ammunition table listing for the amount of bolts that are sold together.

https://discord.com/channels/516367331358801950/1311967093603962963/1315715797888532511

The ammunition table can be found here: https://www.dndbeyond.com/sources/dnd/br-2024/equipment#AmmunitionVaries