Customer assets can be linked to those on a new quotation.
Asset mapping is enabled on a per-product classification basis - for example, you may wish to enable this for renewals and upgrades but not for new items. Your classification names will vary depending on your setup.
Users with Settings access can configure this this from the Product Classification area.
Select your classification and check Asset Mapping Supported.
The option to Map Opportunity Assets will be available when adding items with the mapping-enabled classifications.
Note - if your instance has quotation-level data capture enabled, then it is possible to map assets to services individually from data capture. This bypasses the Map Opportunity Assets step in the product browser.
However, we recommend enabling this setting for relevant classifications, as it allows for quicker and easier mapping, especially when required in bulk.