You can use the sample code of retrieving orderline items from a parent order below to meet your requirement of retrieving quoteline items from a quote :-
<fetch version="1.0" output-format="xml-platform" mapping="logical" distinct="false">
<entity name="salesorderdetail">
<attribute name="productid" />
<attribute name="manualdiscountamount" />
<attribute name="productdescription" />
<attribute name="priceperunit" />
<attribute name="quantity" />
<attribute name="extendedamount" />
<attribute name="salesorderdetailid" />
<attribute name="volumediscountamount" />
<attribute name="tax" />
<attribute name="productname" />
<attribute name="priceperunit_base" />
<attribute name="lineitemnumber" />
<attribute name="msdyn_costpriceperunit" />
<attribute name="msdyn_costamount" />
<attribute name="baseamount" />
<attribute name="uomid" />
<order attribute="productid" descending="false" />
<filter type="and">
<condition attribute="salesorderid" operator="eq" uitype="salesorder" value="@OrderId" />
</filter>
<link-entity name="salesorder" alias="salesorder" to="salesorderid" from="salesorderid" link-type="outer" visible="false" >
<attribute name="name" />
<attribute name="customerid" />
<attribute name="statecode" />
<attribute name="totalamount" />
<attribute name="discountpercentage" />
<attribute name="description" />
<attribute name="new_productsubgroupid" />
<attribute name="new_masterproductgroupid" />
<attribute name="quotenumber" />
<attribute name="ownerid" />
<attribute name="createdon" />
<attribute name="quoteid" />
<attribute name="effectiveto" />
<attribute name="effectivefrom" />
</link-entity>
</entity>
</fetch>